New details about collusion between the RUC and loyalist killers in the murder of Belfast solicitor Pat Finucane have emerged today.

A previously unseen chapter of the investigation carried out by John Stevens into claims of collusion has revealed that the RUC deliberately destroyed vital evidence in the case.

The murder of Mr Finucane in front of his wife and family in 1989 was one of the most controversial killings of the Troubles.

The family of the murdered Belfast solicitor, says it expects the Irish Government to continue supporting its campaign for a public inquiry into the circumstances of the killing.

When Mr Stevens published his final report into collusion, known as Stevens 3 back in 2003, it contained four chapters.

Following a four-year legal battle under the UK's Freedom of Information Act, RTÉ obtained Chapter Six.

Entitled 'Murder Investigation', the chapter discussed the RUC's handling of the investigation into Mr Finucane's killing.

The chapter also covered that of a Protestant, Brian Adam Lambert, who was also killed by loyalists who mistook him for a Catholic.

In this newly revealed Chapter Six, Stevens was highly critical of the RUC, saying "by any standards the investigation of these two murders was inadequate."

He pointed out that the policy book, where all decisions regarding the hunt for Mr Funcane's killers were recorded, could not be found.

Exhibit handling was poor overall, and vital evidence could not be found because there were no records to show what happened to them.

He wrote: "Certain documents and other key exhibits are missing. The loss of the samples retrieved from the getaway vehicle used in the murder of Patrick Finucane has prevented new evidential opportunities from being realised," 

However, his strongest criticism was levelled at the way the RUC handled one of the murder weapons - a Browning pistol.

The pistol was recovered by the police but then given back to the British army from where it had been stolen by loyalists sometime previously.

Mr Stevens wrote: "This was not a case of administrative oversight, or even some loss occasioned by a lack of care. I believe it was a clear and deliberate decision to relinquish control of a key exhibit, resulting in the destruction of vital evidence,” 

"The lack of records has prevented the identification of the person responsible for this decision," he added.

The consequences of this were obvious, with allegations made from the start of collusion between the security forces and loyalist paramilitaries, Mr Stevens said.